Hi Mathias,
On Mar 1, 2011, at 8:21 AM, Mathias Wilhelm wrote:
> Hi Quincey,
> Quincey Koziol wrote:
>>> I am using compound data types with vlen strings and integers. The struct
>>> containing the strings and integers also contains a couple of methods,
>>> which prevents me from using the HOFFSET macro, so I used sizeof() and/or
>>> the getSize() method from the H5 data types to determine the offset of the
>>> components. This works under my personal 32-bit system, but ends with a
>>> segmentation fault under a 64-bit system.
>>> I found out that the offset determined by HOFFSET is different from the
>>> sizeof() and getSize() methods. I avoided this problem by inserting the int
>>> as the last element.
>>> Is this a general problem/issue or due wrong usage?
>> You should use HOFFSET for inserting your fields into the compound
>> datatype. The compiler may insert padding before/after fields in the struct
>> and that information is not reflected in the value returned from getSize().
> I would like to use HOFFSET, but since my structs have several methods my
> compiler gives:
>
> x.cpp:301: warning: invalid access to non-static data member ‘main1(int,
> char**)::Test::id’ of NULL object
> x.cpp:301: warning: (perhaps the ‘offsetof’ macro was used incorrectly)
>
> because they are non-PODs.
>
> I just found a solution for it. Is this a proper way to do it?
>
> struct AData {//contains only variables
> //variables
> int acc;
> char* id;
> };
>
> struct A : AData { //contains only functions
> //some functions
> }
>
> Using the HOFFSET(AData, id) macro compiles now without warnings and can be
> used in the insertMember function of CompType.
Looks OK to me, but I'm far from enough of a C++ expert to comment
about the style. :-) You could also just use the offsetof() macro directly,
if that works better.
Quincey
> FYI:
> My compound data structure is quite complex and consists of several nested
> VLEN data types, including strings and other VLEN-data as well as atomic
> types. I need those functions to convert data structures from other API's to
> H5 compound data types, but also for memory management.
>
> ~Mathias
>
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